one of the benefits of using a packet switched solution is that it’s expandable in the future… adding extra terminals anywhere there’s networking is pretty powerful - you can change your mind about location, or even technology in general and not have to worry

… and it’s probably much easier to extend on in the future too - say open source AI assistants get better, you might want to build one that integrates with timers etc, that’s much easier with packet switched … or even more likely, you want to broadcast to the intercom from outside your house or even just make mobile phones able to be transmitters inside the house

you’re totally right that simple point to point intercom stuff like that is a much simpler solution, but packet switched is king for a lot of future-proofing reasons - perhaps not something that OP cares about (a project completed is better than a perfect plan not begun), but worth mentioning